Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal form of cancer. In most patients, detection is at an advanced stage and the outcome is poor. This project is directed towards development of a molecularly targeted ultrasound contrast agent with potential to detect early stage disease while still curable. In Phase I of this project, we incorporated the engineered human single-chain variable fragment (scFv) containing a C-terminal cysteine into maleimide-bearing phospholipid-coated perfluoropropane microbubbles (MB), and in in vivo testing of Thy1- targeted MB for PDAC detection in transgenic mice detected PDAC tumors < 2-mm in size. Furthermore, signal intensity obtained from these MB was 7x that obtained from non-targeted MB and over 1.5x that obtained from non-clinically translatable MB prepared by reaction of biotinylated scFv with streptavidin-coated MB. Overarching Hypothesis: A clinically translatable Thy1-targeted MB will improve visualization and detection of PDAC and enable diagnosis at earlier stage disease to ultimately improve survival of PDAC patients. Research Objectives: We will optimize conditions of conjugation chemistry to yield a product that can undergo formal development as a drug candidate. We will scale up production and produce sufficient material for investigational new drug (IND) enabling studies. We will perform toxicology studies necessary to support an IND. Specific Aim 1. Optimization of preparation of anti-Thy1 scFv to DSPE-PEG5000, purification of the bioconjugate, formulation of the phospholipids suspension containing the DSPE-PEG5000-Mal-scFv, and in vitro binding evaluation of Thy1 targeted MB as a drug candidate. Milestone: A scFv bioconjugate that binds to Thy1 with < 100nM KD with greater than 95% purity. Specific Aim 2. c-GMP preparation of Thy1-targeted MB and validation of drug product in vivo. Milestone: Preparation of sufficient c-GMP Thy1-targeted MB formulation for IND-enabling studies, single dose MTD similar to control MB and demonstration of in vivo binding ability of Thy1-targeted MB. Specific Aim 3. Complete toxicology studies sufficient to support an IND. Outcome of Research: Successful completion of the proposed Aims will yield a Thy1-targeted MB intended for formal drug development and will allow submission of an IND for testing in first-in-human clinical trials.